Motor vehicle cooling systems for cooling engine coolant and refrigerant vapor are known in which a refrigerant condenser unit is located upstream from the cooling air inlet side of the radiator for extracting heat from the coolant system for a liquid cooled engine. Such refrigerant condensers have separate air centers and the radiator has separate air centers.
In order to meet space and weight design constraints and inlet air stream flow patterns in a motor vehicle, a combined radiator and condenser apparatus has been utilized as disclosed in U.S. Pat. No. 5,009,262, issued Apr. 23, 1991 in the name of Halstead et al., and assigned to the assignee of the subject invention. The combination apparatus provides thin gauge, corrugated aluminum air centers which are common for both the radiator and condenser, and each of the radiator and condenser units share a common tank member and common header plates. An extruded tank has an integral internal partition which separates the extruded tank into a coolant chamber and a high pressure refrigerant chamber. The tube passes of both the radiator and the condenser are bonded to an integral wall of the extruded tank at tube access slots therein. The tubes have the same air centers for defining a single air flow pass through both the radiator and the condenser.
A concern is the heat conduction between the coolant tank and refrigerant tank. The coolant has a temperature approximately 100.degree. F. higher than that of the refrigerant. This temperature difference results in the heat conduction from the coolant to the refrigerant, reducing the performance of the air conditioning system.
It has been proposed to utilize narrow slits to prevent such heat conduction. The slits are located within the extruded tank wholly extending within the partition walls thereof and having open ends at the ends of the longitudinal tanks, as proposed in U.S. Ser. No. 07/863,905. However, this design is of higher cost for extrusion tooling, and also may be prone to plugging at the ends by corrosive road salt.